Fields of study include: astrophysics, celestial mechanics, and cosmology.

Astronomy is considered by some to be the oldest recorded science. This concept is based on records from ancient Babylonia, China, Egypt, and Mexico.

The first true astronomers are said to be the Greeks, who deduced the earth to be a sphere and attempted to measure its size. A summary of Greek astronomy came to us from Ptolemy of Alexandria's Almagest.

The Arabs developed the astrolabe and produced good star catalogs while in 1543, the Polish astronomer Copernicus demonstrated that the sun, not the earth, is the center of our planetary system

The Italian scientist Galileo was the first to use a telescope for astronomical study, 1609-1610.

The British astronomer William Herschel's suggestions on the shape of our galaxy were verified in 1923 by the U.S. astronomer Edwin Hubble's telescope at the Mount Wilson Observatory in California.

Recent extension of the powers of astronomy to explore the universe has been made possible in the use of rockets, satellites, space stations, and space probes, while the launching of the Hubble Space Telescope into permanent orbit in 1990 has made it possible for the detection of celestial phenomena seven times more distant than by any earth-based telescope.

A clock that, in addition to telling the time, was designed to show the positions of the sun, moon, and other celestial bodies.

1. The average distance from the earth to the sun, which equals 149,597,870 kilometers or 92,955,800 miles.

For simplicity, an AU is usually rounded off to 93,000,000 miles or 149,637,000 kilometers.

2. An astronomical unit is used to describe planetary distances.

Light travels this distance in approximately 8.3 minutes.